Field of the Invention
The present invention relates to a lithography apparatus, a determination method, and a method of manufacturing an article.
Description of the Related Art
Recently, semiconductor device manufacturing techniques, particularly, micropatterning techniques have made significant progress. Along with this, the number of chips obtainable from one substrate is increasing. There is a need for a technique for ensuring effective chips even in edge shots (partial shots) at the peripheral portion of a substrate to increase the number of effective chips obtained from one substrate (that is, increase the yield).
As semiconductor devices are micropatterned more and more, a projection optical system in, for example, an exposure apparatus serving as one of lithography apparatuses achieves a high NA, and the depth of focus tends to become narrow. Hence, the exposure apparatus is requested to transfer a pattern up to the peripheral portion of a substrate while maintaining a predetermined line width (that is, without defocusing). However, if the substrate holding ability by a substrate chuck (holding surface) is poor, the shape of the peripheral portion of a substrate greatly changes. It is more difficult to ensure the depth of focus at the peripheral portion of a substrate, compared to the central portion of the substrate.
To minimize the defocus, the substrate holding ability by the substrate chuck needs to be maximized. It is therefore important to set a substrate in an optimal positional relationship with respect to the substrate chuck, that is, make the center of the substrate chuck coincide with that of the substrate without a deviation.
To achieve this, Japanese Patent No. 4493272 has proposed a technique of transporting a substrate on which a mark is formed (patterned), detecting the mark by a scope when the substrate is held by a substrate chuck, and obtaining and feeding back the shift amount of the substrate held by the substrate chuck. Japanese Patent Publication No. 5-087008 has proposed a technique of applying a vacuum pressure from the surface of a substrate (that is, mechanically pressing the substrate) to bring the substrate into tight contact with a substrate chuck, thereby improving the flatness of the substrate held by the substrate chuck, regardless of the shift amount of the substrate held by the substrate chuck.
However, in the technique disclosed in Japanese Patent No. 4493272, the positional relationship between the substrate chuck and the substrate is adjusted based on the position of a mark formed on the substrate. If the position of the mark formed on the substrate shifts from a set position, the center of the substrate chuck and the center of the substrate cannot coincide with each other. Since the mark formed on the substrate is detected by the scope, a detection error may arise from the attachment error of the scope itself, or the like.
To the contrary, when a substrate is mechanically pressed from its surface, as in the technique disclosed in Japanese Patent Publication No. 5-087008, a device pattern formed on the substrate may be damaged, or a foreign substance may attach to the substrate.